This section formulates an optimization problem that exploits the interrelation of the system performance and the available resources per transmitter (i.e., limited transmit power and fronthaul capacity). Namely, this section tackles an optimization problem that maximizes a network-wide sum-rate, subject to resource availability constraints, by jointly considering user association and the respective beamforming vectors. The presented problem features a non-convex optimization problem over mixed discrete (user-association) and continuous (beamforming) optimization variables. This section tackles the intricacies of the optimization problems using well-chosen mathematical reformulation techniques, such as sparse beamforming using both the \(\ell _1\) -norm re-weighting technique, and fractional programming (FP) transformations, first proposed in [1]}, [2]}.
